need advice on bush hog driveshaft

Hi, I just bought a used Bush Hog 2510 and am trying to match it up to my Ford 5900. My question is this, in the on line bush hog manual it appears the pull bar point must be 14 inches past the PTO shaft on the tractor. It also says you must have at least 6 inches of overlap in your driveshaft. The way my pull bar is right now, I only have about 2 or 3 inches of the one shaft inside the other. I know I can move my pull bar in some, but I would need to move it in at least 4 inches to have the adequate lap, but this may only leave me 12 inches or so of distance from the shaft to the pull bar center hole. Will this work, or do I HAVE to stick to the 14" recomendation?? Thanks for any help

Re: need advice on bush hog driveshaft

If I understand what you are saying, when you move the drawbar in to the next hole, the shaft is overlapped more than recommended. If this is the case, how much stroke is remaining before it bottoms out (the whole way in)? If you have 4 inches or more, I wouldnt worry about it. Using it with only 3 inches of overlap is not a good idea, but Im sure you know that.

Re: need advice on bush hog driveshaft

My GUESS, and it's only a guess, is the reason for specing the drawbar pivot point distance from the end of the tractor pTO shaft is to position the U-Joint of the implement PTO shaft inthe proper relationship to the pivot point of the implement hitch. Changing this could cause binding or worse when making turns. I would stick with the 14"

If you can add an extention to your tractor PTO as Roy suggests and then can set your drawbar to the 14" spec that would work

Re: need advice on bush hog driveshaft

Since you bought it used, there's a chance the previous owner at one time replaced the PTO shaft with one that was too short. The Bush Hog recommended 6" overlap would make me uncomfortable. I mow undulating ground, and some of the crests and swales flex my mower shafts more than 6". I select PTO shafts with a minimum 1/3 overlap. And if an implement comes with a shaft that I feel is too short, I get a longer one.

Most shafts are sold on the basis of overall length, so you really need a tape measure to get specific. But just for example purposes I'm gonna guess your 10' pull type RC may use something in the neighborhood of a 51" (compressed) PTO shaft. With a RC of that size, you should be using a slip clutch. So that will take the actual compressed overlap down to maybe 42". Which means you can extend it to 56", and still have a 14" overlap.

Don't take these for exact numbers, you'll have to measure your own tractor/mower configuration. It's just that I personally wouldn't feel comfortable with only 6" of overlap. That said, if you mow billiard tables, maybe I'm making a big deal outa nothing.

Re: need advice on bush hog driveshaft

on top of what Roy has suggested, they also make a slip on Over-running clutch that will add 6" to the length of the pto shaft.... and also allow for freewheeling of the mower when you shut down the pto unit while operating the machine. My over running clutch slips on and locks just like a regular pto device. Just make sure you dont get one that needs to be pinned on...as you cant remove it later on then.

Re: need advice on bush hog driveshaft

Originally Posted by grsthegreat

on top of what Roy has suggested, they also make a slip on Over-running clutch that will add 6" to the length of the pto shaft.... and also allow for freewheeling of the mower when you shut down the pto unit while operating the machine. My over running clutch slips on and locks just like a regular pto device. Just make sure you dont get one that needs to be pinned on...as you cant remove it later on then.

I'm thinking that overrunning clutch might be a better way to go, at least with some implements (those with high inertial loads such as a cutter or chipper)...especially after that thread that devolved into a "PTO Brake" pissing contest (original topc was PTO Chippers, if you recall).

One thing I have read, but no supporting links...use of a PTO extension can cause premature wear on the tractor's PTO mechanism. IIRC, it was due to the lengthening of the stub shaft (of the tractor) putting more loads on the bearings.
I use my extension ("adapter") with my chipper...that's the only implement. Since I probably don't put more then 10-12 hours (total) on the chipper in the course of a year, I don't see wear being a major issue.

Roy Jackson
”"Any government that does not trust its citizens with firearms is either a tyranny, or planning to become one."
-Joseph P. Martino

Re: need advice on bush hog driveshaft

Originally Posted by greg_g

Since you bought it used, there's a chance the previous owner at one time replaced the PTO shaft with one that was too short. The Bush Hog recommended 6" overlap would make me uncomfortable. I mow undulating ground, and some of the crests and swales flex my mower shafts more than 6". I select PTO shafts with a minimum 1/3 overlap. And if an implement comes with a shaft that I feel is too short, I get a longer one.

Most shafts are sold on the basis of overall length, so you really need a tape measure to get specific. But just for example purposes I'm gonna guess your 10' pull type RC may use something in the neighborhood of a 51" (compressed) PTO shaft. With a RC of that size, you should be using a slip clutch. So that will take the actual compressed overlap down to maybe 42". Which means you can extend it to 56", and still have a 14" overlap.

Don't take these for exact numbers, you'll have to measure your own tractor/mower configuration. It's just that I personally wouldn't feel comfortable with only 6" of overlap. That said, if you mow billiard tables, maybe I'm making a big deal outa nothing.

//greg//

The way mine is set up, the shaft I am talking about is pretty short, Im going to try to show a pic, kinda seems like there isnt a lot of room to play with. I also want to add I really appreciate your guys input, I dont know much about this, but with some help I will figure it out. I have bush hogged quite a bit before with a smaller tractor and a 5 foot bush hog, there just a lot more things to consider with a larger machine. I also noticed that with the draw bar in the position it is in now, that the hoses were a little snug when I hooked them up to unload it off the trailer, so that too suggests the draw bar needs to be shortened.

Re: need advice on bush hog driveshaft

In the order of cost to you I first hope your draw bar is adjustable like mine. I can pin it long or short. Hopefully yours is the same. If yes, push it in and pin it with the least amount possible sticking out. Downside may be the pull bar hitting a tire in turns. If not, the PTO adapter and ORC will give you a short extension - but don't expect more than about 4". On the negative side, there's the potential wear increase factor involved with this option. Third would be to modify the shaft segment that goes between the tractor and the pull bar. You can buy a splined coupler and female shaft alone, but get a shaft that's considerably longer than the one you're replacing. That will in effect get the tractor end of the shaft closer to your PTO spline. It does however, make the forward non-overlapped section vulnerable to twisting. Last but most expensive (yet safest), would be to replace the whole PTO shaft section between the tractor and the pull bar.

Re: need advice on bush hog driveshaft

The actual ASAE standard distance for a 540 RPM PTO is 14" from the end of the tractor's PTO shaft to the center of the drawbar pin hole. If the new to you cutter has a conventional PTO shaft (not a Constant Velocity joint at the front yoke) the driveline will chatter like mad in a moderate turn with the hitch attached as per ASAE standards due to the hitch pin not being centered between the front and rear PTO shaft U-joints. Shortening the tractor drawbar, or adding a shaft extender or slipclutch to the tractor's output shaft will cause more driveline chatter and EXPONENTIALLY increase the possibility of twisting/breaking your tractor's PTO shaft off.
The correct course of action is to replace the cutter's PTO shaft tubes (and shielding, if necessary) to provide the required minimum overlap when the tractor drawbar is set to the 14" ASAE standard. If longer hoses are required, add short hoses, or replace the existing hoses with longer ones. Ideally, the R/C would have a PTO shaft of the proper length and a CV joint at the front. Cost of this option would likely be prohibitive.